On 2021/10/7 19:27, Konstantin Ananyev wrote:
> Copy public function pointers (rx_pkt_burst(), etc.) and related
> pointers to internal data from rte_eth_dev structure into a
> separate flat array. That array will remain in a public header.
> The intention here is to make rte_eth_dev and related structures internal.
> That should allow future possible changes to core eth_dev structures
> to be transparent to the user and help to avoid ABI/API breakages.
> The plan is to keep minimal part of data from rte_eth_dev public,
> so we still can use inline functions for fast-path calls
> (like rte_eth_rx_burst(), etc.) to avoid/minimize slowdown.
> The whole idea beyond this new schema:
> 1. PMDs keep to setup fast-path function pointers and related data
> inside rte_eth_dev struct in the same way they did it before.
> 2. Inside rte_eth_dev_start() and inside rte_eth_dev_probing_finish()
> (for secondary process) we call eth_dev_fp_ops_setup, which
> copies these function and data pointers into rte_eth_fp_ops[port_id].
> 3. Inside rte_eth_dev_stop() and inside rte_eth_dev_release_port()
> we call eth_dev_fp_ops_reset(), which resets rte_eth_fp_ops[port_id]
> into some dummy values.
> 4. fast-path ethdev API (rte_eth_rx_burst(), etc.) will use that new
> flat array to call PMD specific functions.
> That approach should allow us to make rte_eth_devices[] private
> without introducing regression and help to avoid changes in drivers code.
>
> Signed-off-by: Konstantin Ananyev <konstantin.anan...@intel.com>
> ---
> lib/ethdev/ethdev_private.c | 52 ++++++++++++++++++++++++++++++++++
> lib/ethdev/ethdev_private.h | 7 +++++
> lib/ethdev/rte_ethdev.c | 27 ++++++++++++++++++
> lib/ethdev/rte_ethdev_core.h | 55 ++++++++++++++++++++++++++++++++++++
> 4 files changed, 141 insertions(+)
>
> diff --git a/lib/ethdev/ethdev_private.c b/lib/ethdev/ethdev_private.c
> index 012cf73ca2..3eeda6e9f9 100644
> --- a/lib/ethdev/ethdev_private.c
> +++ b/lib/ethdev/ethdev_private.c
> @@ -174,3 +174,55 @@ rte_eth_devargs_parse_representor_ports(char *str, void
> *data)
> RTE_LOG(ERR, EAL, "wrong representor format: %s\n", str);
> return str == NULL ? -1 : 0;
> }
> +
> +static uint16_t
> +dummy_eth_rx_burst(__rte_unused void *rxq,
> + __rte_unused struct rte_mbuf **rx_pkts,
> + __rte_unused uint16_t nb_pkts)
> +{
> + RTE_ETHDEV_LOG(ERR, "rx_pkt_burst for unconfigured port\n");
> + rte_errno = ENOTSUP;
> + return 0;
> +}
> +
> +static uint16_t
> +dummy_eth_tx_burst(__rte_unused void *txq,
> + __rte_unused struct rte_mbuf **tx_pkts,
> + __rte_unused uint16_t nb_pkts)
> +{
> + RTE_ETHDEV_LOG(ERR, "tx_pkt_burst for unconfigured port\n");
> + rte_errno = ENOTSUP;
> + return 0;
> +}
> +
> +void
> +eth_dev_fp_ops_reset(struct rte_eth_fp_ops *fpo)
The port_id parameter is preferable, this will hide rte_eth_fp_ops as much as
possible.
> +{
> + static void *dummy_data[RTE_MAX_QUEUES_PER_PORT];
> + static const struct rte_eth_fp_ops dummy_ops = {
> + .rx_pkt_burst = dummy_eth_rx_burst,
> + .tx_pkt_burst = dummy_eth_tx_burst,
> + .rxq = {.data = dummy_data, .clbk = dummy_data,},
> + .txq = {.data = dummy_data, .clbk = dummy_data,},
> + };
> +
> + *fpo = dummy_ops;
> +}
> +
> +void
> +eth_dev_fp_ops_setup(struct rte_eth_fp_ops *fpo,
> + const struct rte_eth_dev *dev)
Because fp_ops and eth_dev is a one-to-one correspondence. It's better only use
port_id parameter.
> +{
> + fpo->rx_pkt_burst = dev->rx_pkt_burst;
> + fpo->tx_pkt_burst = dev->tx_pkt_burst;
> + fpo->tx_pkt_prepare = dev->tx_pkt_prepare;
> + fpo->rx_queue_count = dev->rx_queue_count;
> + fpo->rx_descriptor_status = dev->rx_descriptor_status;
> + fpo->tx_descriptor_status = dev->tx_descriptor_status;
> +
> + fpo->rxq.data = dev->data->rx_queues;
> + fpo->rxq.clbk = (void **)(uintptr_t)dev->post_rx_burst_cbs;
> +
> + fpo->txq.data = dev->data->tx_queues;
> + fpo->txq.clbk = (void **)(uintptr_t)dev->pre_tx_burst_cbs;
> +}
> diff --git a/lib/ethdev/ethdev_private.h b/lib/ethdev/ethdev_private.h
> index 3724429577..5721be7bdc 100644
> --- a/lib/ethdev/ethdev_private.h
> +++ b/lib/ethdev/ethdev_private.h
> @@ -26,4 +26,11 @@ eth_find_device(const struct rte_eth_dev *_start,
> rte_eth_cmp_t cmp,
> /* Parse devargs value for representor parameter. */
> int rte_eth_devargs_parse_representor_ports(char *str, void *data);
>
> +/* reset eth fast-path API to dummy values */
> +void eth_dev_fp_ops_reset(struct rte_eth_fp_ops *fpo);
> +
> +/* setup eth fast-path API to ethdev values */
> +void eth_dev_fp_ops_setup(struct rte_eth_fp_ops *fpo,
> + const struct rte_eth_dev *dev);
Some drivers control the transmit/receive function during operation. E.g.
for hns3 driver, when detect reset, primary process will set rx/tx burst to
dummy, after
process reset, primary process will set the correct rx/tx burst. During this
process, the
send and receive threads are still working, but the bursts they call are
changed. So:
1. it is recommended that trace be deleted from the dummy function.
2. public the eth_dev_fp_ops_reset/setup interface for driver usage.
> +
> #endif /* _ETH_PRIVATE_H_ */
> diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c
> index c8abda6dd7..9f7a0cbb8c 100644
> --- a/lib/ethdev/rte_ethdev.c
> +++ b/lib/ethdev/rte_ethdev.c
> @@ -44,6 +44,9 @@
> static const char *MZ_RTE_ETH_DEV_DATA = "rte_eth_dev_data";
> struct rte_eth_dev rte_eth_devices[RTE_MAX_ETHPORTS];
>
> +/* public fast-path API */
> +struct rte_eth_fp_ops rte_eth_fp_ops[RTE_MAX_ETHPORTS];
> +
> /* spinlock for eth device callbacks */
> static rte_spinlock_t eth_dev_cb_lock = RTE_SPINLOCK_INITIALIZER;
>
> @@ -578,6 +581,8 @@ rte_eth_dev_release_port(struct rte_eth_dev *eth_dev)
> rte_eth_dev_callback_process(eth_dev,
> RTE_ETH_EVENT_DESTROY, NULL);
>
> + eth_dev_fp_ops_reset(rte_eth_fp_ops + eth_dev->data->port_id);
> +
> rte_spinlock_lock(ð_dev_shared_data->ownership_lock);
>
> eth_dev->state = RTE_ETH_DEV_UNUSED;
> @@ -1787,6 +1792,9 @@ rte_eth_dev_start(uint16_t port_id)
> (*dev->dev_ops->link_update)(dev, 0);
> }
>
> + /* expose selection of PMD fast-path functions */
> + eth_dev_fp_ops_setup(rte_eth_fp_ops + port_id, dev);
> +
> rte_ethdev_trace_start(port_id);
> return 0;
> }
> @@ -1809,6 +1817,9 @@ rte_eth_dev_stop(uint16_t port_id)
> return 0;
> }
>
> + /* point fast-path functions to dummy ones */
> + eth_dev_fp_ops_reset(rte_eth_fp_ops + port_id);
> +
> dev->data->dev_started = 0;
> ret = (*dev->dev_ops->dev_stop)(dev);
> rte_ethdev_trace_stop(port_id, ret);
> @@ -4567,6 +4578,14 @@ rte_eth_mirror_rule_reset(uint16_t port_id, uint8_t
> rule_id)
> return eth_err(port_id, (*dev->dev_ops->mirror_rule_reset)(dev,
> rule_id));
> }
>
> +RTE_INIT(eth_dev_init_fp_ops)
> +{
> + uint32_t i;
> +
> + for (i = 0; i != RTE_DIM(rte_eth_fp_ops); i++)
> + eth_dev_fp_ops_reset(rte_eth_fp_ops + i);
> +}
> +
> RTE_INIT(eth_dev_init_cb_lists)
> {
> uint16_t i;
> @@ -4735,6 +4754,14 @@ rte_eth_dev_probing_finish(struct rte_eth_dev *dev)
> if (dev == NULL)
> return;
>
> + /*
> + * for secondary process, at that point we expect device
> + * to be already 'usable', so shared data and all function pointers
> + * for fast-path devops have to be setup properly inside rte_eth_dev.
> + */
> + if (rte_eal_process_type() == RTE_PROC_SECONDARY)
> + eth_dev_fp_ops_setup(rte_eth_fp_ops + dev->data->port_id, dev);
> +
> rte_eth_dev_callback_process(dev, RTE_ETH_EVENT_NEW, NULL);
>
> dev->state = RTE_ETH_DEV_ATTACHED;
> diff --git a/lib/ethdev/rte_ethdev_core.h b/lib/ethdev/rte_ethdev_core.h
> index 51cd68de94..d5853dff86 100644
> --- a/lib/ethdev/rte_ethdev_core.h
> +++ b/lib/ethdev/rte_ethdev_core.h
> @@ -50,6 +50,61 @@ typedef int (*eth_rx_descriptor_status_t)(void *rxq,
> uint16_t offset);
> typedef int (*eth_tx_descriptor_status_t)(void *txq, uint16_t offset);
> /**< @internal Check the status of a Tx descriptor */
>
> +/**
> + * @internal
> + * Structure used to hold opaque pointers to internal ethdev Rx/Tx
> + * queues data.
> + * The main purpose to expose these pointers at all - allow compiler
> + * to fetch this data for fast-path ethdev inline functions in advance.
> + */
> +struct rte_ethdev_qdata {
> + void **data;
> + /**< points to array of internal queue data pointers */
> + void **clbk;
> + /**< points to array of queue callback data pointers */
> +};
> +
> +/**
> + * @internal
> + * fast-path ethdev functions and related data are hold in a flat array.
> + * One entry per ethdev.
> + * On 64-bit systems contents of this structure occupy exactly two 64B lines.
> + * On 32-bit systems contents of this structure fits into one 64B line.
> + */
> +struct rte_eth_fp_ops {
> +
> + /**
> + * Rx fast-path functions and related data.
> + * 64-bit systems: occupies first 64B line
> + */
> + eth_rx_burst_t rx_pkt_burst;
> + /**< PMD receive function. */
> + eth_rx_queue_count_t rx_queue_count;
> + /**< Get the number of used RX descriptors. */
> + eth_rx_descriptor_status_t rx_descriptor_status;
> + /**< Check the status of a Rx descriptor. */
> + struct rte_ethdev_qdata rxq;
> + /**< Rx queues data. */
> + uintptr_t reserved1[3];
> +
> + /**
> + * Tx fast-path functions and related data.
> + * 64-bit systems: occupies second 64B line
> + */
> + eth_tx_burst_t tx_pkt_burst;
Why not place rx_pkt_burst/tx_pkt_burst/rxq /txq to the first cacheline ?
Other function, e.g. rx_queue_count/descriptor_status are low frequency call
functions.
> + /**< PMD transmit function. */
> + eth_tx_prep_t tx_pkt_prepare;
> + /**< PMD transmit prepare function. */
> + eth_tx_descriptor_status_t tx_descriptor_status;
> + /**< Check the status of a Tx descriptor. */
> + struct rte_ethdev_qdata txq;
> + /**< Tx queues data. */
> + uintptr_t reserved2[3];
> +
> +} __rte_cache_aligned;
> +
> +extern struct rte_eth_fp_ops rte_eth_fp_ops[RTE_MAX_ETHPORTS];
> +
>
> /**
> * @internal
>
